Chemical sensitization of photothermographic silver halide emulsions

- Imation Corp.

Chemical sensitization of silver halide photothermographic emulsions used in photothermographic elements, can be effected by the decomposition of sulfur containing compounds on or around the surface of the silver halide grains, usually under oxidizing conditions at elevated temperatures. Alignment of the sulfur containing compounds on the surface of the grains, can be accomplished with spectral sensitizing dyes and appears to be particularly effective in providing strong chemical sensitization effects.

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Claims

1. A method for preparing a photothermographic emulsion comprising the steps of:

(a) providing a photothermographic emulsion comprising silver halide grains and a non-photosensitive silver source;
(b) providing an organic sulfur-containing compound positioned on or around the silver halide grains; and
(c) chemically sensitizing the silver halide grains by decomposing the organic sulfur-containing compound on or around the silver halide grains in an oxidizing environment.

2. The method of claim 1 which the chemical sensitizing step comprises reacting the sulfur compound from the decomposed organic sulfur-containing compound with the silver halide grains.

3. The method of claim 1 in which the decomposing produces HSBr which chemically sensitizes the silver halide grains.

4. The method of claim 1 in which after chemical sensitization of said silver halide grains, a spectral sensitizing dye is added to said photothermographic emulsion to spectrally sensitize said emulsion.

5. The method of claim 1 wherein said silver halide grains are iridium-doped silver halide grains.

6. The method of claim 1 wherein said silver halide grains comprise silver halide grains which are iridium doped core-shell silver halide grains and after chemical sensitization of said silver halide grains, a spectral sensitizing dye is added to said photothermographic emulsion to spectrally sensitize said emulsion.

7. The method of claim 6 wherein said spectral sensitizing dye sensitizes the chemically sensitized silver halide grains of the photothermographic emulsion to the red or infrared region of the electromagnetic spectrum between 600 nm and 1000 nm.

8. The method of claim 1 further comprising adding a reducing agent to the sensitized photothermographic emulsion.

9. The method of claim 1 wherein the sulfur-containing compound comprises a ring structure having --S-- or ##STR21## within the ring.

10. A method for preparing a photothermographic emulsion comprising the steps of:

(a) providing a photothermographic emulsion comprising silver halide grains and a non-photosensitive silver source;
(b) providing a sulfur-containing spectral sensitizing dye positioned on or around the silver halide grains; and
(c) chemically sensitizing the silver halide grains by decomposing the spectral sensitizing dye on or around the silver halide grains.

11. The method of claim 10 in which after chemical sensitization of said silver halide grains, a second spectral sensitizing dye is added to said photothermographic emulsion to spectrally sensitize said emulsion.

12. A method for preparing a photothermographic emulsion comprising the steps of:

(a) providing a photothermographic emulsion comprising silver halide grains and a non-photosensitive silver source;
(b) providing a sulfur-containing compound comprising a thiohydantoin nucleus, a rhodanine nucleus, or a 2-thio-4-oxo-oxazolidine nucleus positioned on or around the silver halide grains; and
(c) chemically sensitizing the silver halide grains by decomposing the sulfur-containing compound on or around the silver halide grains.

13. A method for preparing a photothermographic emulsion comprising the steps of:

(a) providing a photothermographic emulsion comprising silver halide grains and a non-photosensitive silver source;
(b) providing a sulfur-containing compound positioned on or around the silver halide grains; and
(c) chemically sensitizing the silver halide grains by providing an oxidizing compound which causes the decomposing of the sulfur-containing compound on or around the silver halide grains.

14. The method of claim 13 wherein the oxidizing compound is present in a solution, said solution is in contact with said silver halide grains, and the chemical sensitizing step occurs at a temperature above about 20.degree. C.

15. The method of claim 14 where the temperature is between about 20.degree. C. and about 40.degree. C.

16. The method of claim 13 wherein said oxidizing compound is pyridinium hydrobromide perbromide.

17. A method of forming a sensitized photothermographic emulsion comprising the steps of:

(a) providing a photothermographic emulsion comprising silver halide grains and a non-photosensitive silver source;
(b) providing a sulfur-containing spectral sensitizing dye on or around the silver halide grains;
(c) decomposing the spectral sensitizing dye in an oxidizing environment at a temperature between about 20.degree. C. and about 40.degree. C.;
(d) adding a second spectral sensitizing dye to said photothermographic emulsion to spectrally sensitize said emulsion.

18. A method of making a photothermographic element comprising:

(a) preparing a photothermographic emulsion according to claim 1;
(b) adding a reducing agent and a binder to the photothermographic emulsion;
(c) coating the photothermographic emulsion on a substrate.

19. A method for chemically sensitizing silver halide grains comprising the steps of:

(a) providing a silver halide grains;
(b) providing a sulfur-containing sensitizing dye on or around the surface of silver halide grains; and
(c) oxidatively decomposing the sulfur-containing sensitizing dye thereby chemically sensitizing said grains.
Referenced Cited
U.S. Patent Documents
1623499 April 1927 Sheppard et al.
2131038 September 1938 Brooker et al.
2399083 April 1946 Waller et al.
2444605 December 1948 Heimbach et al.
2489341 November 1949 Waller et al.
2565418 August 1951 Yackel
2566263 August 1951 Trivelli et al.
2588765 March 1952 Robijns et al.
2597915 May 1952 Yutzy et al.
2614928 October 1952 Yutzy et al.
2618556 November 1952 Hewitson et al.
2681294 June 1954 Beguin
2694716 November 1954 Allen et al.
2701245 February 1955 Lynn
2728663 December 1955 Allen et al.
2761791 September 1956 Russell
2839405 June 1958 Jones
2861056 November 1958 Minsk
2886437 May 1959 Piper
2960404 November 1960 Milton et al.
2992101 July 1961 Jelley et al.
3080254 March 1963 Grant, Jr.
3121060 February 1964 Duane
3201678 August 1965 Meixell
3206312 September 1965 Sterman et al.
3220839 November 1965 Herz et al.
3235652 February 1966 Lindsey
3241969 March 1966 Hart et al.
3287135 November 1966 Anderson et al.
3297446 January 1967 Dunn
3297447 January 1967 McVeigh
3330663 July 1967 Weyde et al.
3428451 February 1969 Trevoy
3457075 July 1969 Morgan et al.
3700458 October 1972 Lindholm
3719495 March 1973 Lea
3761279 September 1973 Mauriac et al.
3785830 January 1974 Sullivan et al.
3839049 October 1974 Simons
3846136 November 1974 Sullivan
3847612 November 1974 Winslow
3985565 October 12, 1976 Gabrielsen et al.
3994732 November 1976 Winslow
4001025 January 4, 1977 Cash
4021249 May 3, 1977 Noguchi et al.
4076539 February 28, 1978 Ikenoue et al.
4123274 October 31, 1978 Knight et al.
4123282 October 31, 1978 Winslow
4207108 June 10, 1980 Hiller
4213784 July 22, 1980 Ikenoue et al.
4220709 September 2, 1980 deMauriac
4260677 April 7, 1981 Winslow et al.
4374921 February 22, 1983 Frenchik
4708928 November 24, 1987 Geisler
4725534 February 16, 1988 Kagami et al.
4761361 August 2, 1988 Ozaki et al.
4775613 October 4, 1988 Hirai et al.
5028523 July 2, 1991 Skoug
5135842 August 4, 1992 Kitchin et al.
5158866 October 27, 1992 Simpson et al.
5175081 December 29, 1992 Krepski et al.
5185231 February 9, 1993 Weigel
5226452 July 13, 1993 Muller et al.
5262295 November 16, 1993 Tanaka et al.
5279928 January 18, 1994 Dedio et al.
5281515 January 25, 1994 Delprato et al.
5298390 March 29, 1994 Sakizadeh et al.
5300420 April 5, 1994 Kenney et al.
5310640 May 10, 1994 Markin et al.
5314795 May 24, 1994 Helland et al.
5340613 August 23, 1994 Hanzalik et al.
5380635 January 10, 1995 Gomez et al.
5380644 January 10, 1995 Yonkoski et al.
5382504 January 17, 1995 Shor et al.
5434043 July 18, 1995 Zou et al.
5441866 August 15, 1995 Miller et al.
5460938 October 24, 1995 Kirk et al.
5491059 February 13, 1996 Whitcomb
5496695 March 5, 1996 Simpson et al.
5541054 July 30, 1996 Miller et al.
5541055 July 30, 1996 Ooi et al.
5545505 August 13, 1996 Simpson
5545507 August 13, 1996 Simpson et al.
5545515 August 13, 1996 Murray et al.
5558983 September 24, 1996 Simpson et al.
5635339 June 3, 1997 Murray
5637449 June 10, 1997 Harring et al.
5654130 August 5, 1997 Murray
5686228 November 11, 1997 Murray et al.
5705324 January 6, 1998 Murray
Foreign Patent Documents
0600589 June 1994 EPX
0 627 660 December 1994 EPX
0 713 132 May 1996 EPX
49-13224 February 1974 JPX
51-42529 April 1976 JPX
52-126780 October 1977 JPX
623448 May 1949 GBX
837095 June 1960 GBX
955061 April 1964 GBX
1 325 312 August 1973 GBX
1 447 454 August 1976 GBX
WO 95/23357 August 1995 WOX
Other references
Patent History
Patent number: 5891615
Type: Grant
Filed: Apr 8, 1997
Date of Patent: Apr 6, 1999
Assignee: Imation Corp. (Oakdale, MN)
Inventors: John M. Winslow (South St. Paul, MN), Gary L. Featherstone (Oakdale, MN), Doreen C. Lynch (Afton, MN), James R. Miller (Hudson, WI), Sharon M. Simpson (Lake Elmo, MN), Mark C. Skinner (Afton, MN)
Primary Examiner: Thorl Chea
Attorney: William K. Weimer
Application Number: 8/841,953